1. Field of the Invention
This invention relates to a sander, particularly to one provided with a low load swinging mechanism to upgrade grinding precision.
2. Description of the Prior Art
As shown in FIG. 1, a conventional roller unit 10 of a sander is composed of a positioning base 11, a driving source 12, a sliding base 13 and an emery cloth roller 14. The driving source 12 is installed at one side of the positioning base 11, able to activate the emery cloth roller 14 to rotate and the sliding base 13 to reciprocate along the positioning base 11. The positioning base 11 is provided with a pair of lower dovetail grooves 111 for engaging with a pair of upper dovetail grooves 131 provided in the sliding base 13, so as to enable the sliding base 13 to slide against the emery cloth roller 14 for carrying out sanding. However, as the contacting surface between the lower dovetail grooves 111 and the upper dovetail grooves 131 is so large that a great abrasion resistance is generated, the driving source 12 has to output much load to surpass such an abrasion, possible to prompt vibration to lower grinding precision.